'Watchmen' in the Bible

Listen! Your watchmen lift up their voices,They shout joyfully together;For they will see with their own eyesWhen the Lord restores Zion.

His watchmen are blind,All of them know nothing.All of them are mute dogs unable to bark,Dreamers lying down, who love to slumber;

On your walls, O Jerusalem, I have appointed watchmen;All day and all night they will never keep silent.You who remind the Lord, take no rest for yourselves;